Earliest Multicelluar Life Yet Found - 2.1 billion years old

[Broomstick]

Just heard about this, anyone else have information? Apparently a site of truly excellent preservation has been found in Gabon showing multicelluar life forms dating back 2.1 billion years - over 1.5 billion years before the "Cambrian Explosion" that, until now, was generally considered the dawn of complex, multicelluar life.

Reconstruction:


They remind me of Ediacara fossils - but the Edicarans are MUCH more recent! They come just before the Cambrian Era. Here's an example, Dickinsonia costata:

ScienceDaily (July 1, 2010) — The discovery in Gabon of more than 250 fossils in an excellent state of conservation has provided proof, for the first time, of the existence of multicellular organisms 2.1 billion years ago. This finding represents a major breakthrough: until now, the first complex life forms (made up of several cells) dated from around 600 million years ago.

These new fossils, of various shapes and sizes, imply that the origin of organized life is a lot older than is generally admitted, thus challenging current knowledge on the beginning of life. These specimens were discovered and studied by an international (1) multidisciplinary team of researchers led by Abderrazak El Albani of the Laboratoire "Hydrogéologie, Argiles, Sols et Altérations" (CNRS/Université de Poitiers) (2). Their work, due to be published in Nature on 1st July, will feature on the cover of the journal.

The first traces of life appeared in the form of prokaryotic organisms, in other words organisms without a nucleus, around three and a half billion years ago. Another major event in the history of life, the "Cambrian explosion" some 600 million years ago, marked a proliferation in the number of living species. It was accompanied by a sudden rise in oxygen concentration in the atmosphere. What happened between 3.5 billion and 600 million years ago though? Scientists have very little information about this era, known as the Proterozoic. Yet, it is during this crucial period that life diversified: to the prokaryotes were added the eukaryotes, single or multicelled organisms endowed with a more complex organization and metabolism. These large-sized living beings differ from prokaryotes by the presence of cells possessing a nucleus containing DNA.

While studying the paleo-environment of a fossil-bearing site situated near Franceville in Gabon in 2008, El Albani and his team unexpectedly discovered perfectly preserved fossil remains in the 2.1 billion-year-old sediments. They have collected more than 250 fossils to date, of which one hundred or so have been studied in detail. Their morphology cannot be explained by purely chemical or physical mechanisms. These specimens, which have various shapes and can reach 10 to 12 centimeters, are too big and too complex to be single-celled prokaryotes or eukaryotes. This establishes that different life forms co-existed at the start of the Proterozoic, as the specimens are well and truly fossilized living material.

To demonstrate this, the researchers employed cutting-edge techniques that allowed them to define the nature of the samples and to reconstruct their environment. An ion probe capable of measuring the content of sulfur isotopes made it possible to map the relative distribution of organic matter precisely. This matter is what remains of the living organism, which has been transformed into pyrite (a mineral formed of iron disulfide) during fossilization. This helped the researchers to distinguish the fossils from the Gabonese sediment (made of clay). In addition, using an ultra-sophisticated, high-resolution 3D scanner (also known as X-ray microtomograph), they were able to reconstitute the samples in three dimensions and, in particular, assess their degree of internal organization in great detail, without compromising the integrity of the fossils, since the method is non-invasive. The clearly defined and regular shape of these fossils points to a degree of multicellular organization. These organisms lived in colonies: more than 40 specimens per half square meter were sometimes collected. Consequently, they constitute the oldest multicellular eukaryotes ever described to date.

By studying the sedimentary structures of this site, which is remarkable both for its richness and quality of conservation, the scientists have shown that these organisms lived in a shallow marine environment (20 to 30 meters), often calm but periodically subjected to the combined influence of tides, waves and storms. In order to be able to develop 2.1 billion years ago and become differentiated to a degree never attained previously, the authors suggest that these life forms probably benefited from the significant but temporary increase in oxygen concentration in the atmosphere, which occurred between 2.45 and 2 billion years ago. Then, 1.9 billion years ago, the level of oxygen in the atmosphere fell suddenly.

Until now, it has been assumed that organized multicellular life appeared around 0.6 billion years ago and that before then the Earth was mainly populated by microbes (viruses, bacteria, parasites, etc.). This new discovery moves the cursor of the origin of multicellular life back by 1.5 billion years and reveals that cells had begun to cooperate with each other to form more complex and larger structures than single-celled organisms. Several research avenues now need to be explored: understanding the history of the Gabonese basin and why the necessary conditions were gathered to enable this organized and complex life to exist; further exploring the site to enhance the collection of fossils; but also comparing the history of the Earth's oxygenation with the mineralization of clays. The most urgent task, however, remains the protection of this exceptional site.

Notes:

(1) Made up of around twenty researchers from sixteen different institutions.

(2) With the participation, in France, of the following institutions: the Centre de Microtomographie de l'Université de Poitiers, the Unité "Histoire Naturelle de l'Homme Préhistorique" (CNRS/MNHN), the company "Etudes Recherches Matériaux" of the CRI Biopole de Poitiers, the Unité "Géosciences Rennes" (CNRS/Université de Rennes), BRGM (French Geological Survey), the Laboratoire d'Hydrologie et de Géochimie de Strasbourg (CNRS/Université de Strasbourg), the Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements (CNRS/MNHN/UPMC) and the Laboratoire Géosystèmes (CNRS/Université Lille 1/Université d'Amiens).

[Serafina]

That's awesome.
Could any of the experts on such subjects we have here give their point of how this affects theories about the Cambrian explosion and why it was so rare to find such fossils (did they not fossilize, were they too rare, too many damaged or whatnot)?

Oh, and it will be nice to see how this gets shoved up the creationists ass who use the cambrian explosion as a strawman argument.

[Broomstick]

That's awesome.
Could any of the experts on such subjects we have here give their point of how this affects theories about the Cambrian explosion and why it was so rare to find such fossils (did they not fossilize, were they too rare, too many damaged or whatnot)?

Won't call myself an expert, but I think I can answer why such fossils are so rare.

These fossils have no hard parts. The conditions to fossilize soft tissues in any detail are rare. Usually they involve very, very fine sediments that don't move much normally but are subjected to occasional sharp shifts such as landslides, and while the critters need oxygen the preservation normally occurs in environments that reduce biological activity and thus limit decay, such as oxygen free or hyper salty environements. So the mechanism involves abrupt burial in very fine, decay-inhibiting sediment. Not a terribly common occurrence even by fossil standards. The techinical term for such deposits is conservation lagerstaette (Yes, that is the correct English term, and yes, the second half is a German word. Another English theft borrowing, what can I say?)

Even if the Cambrian no longer represents the first multicelluar organisms, it would still mark the start of hard body parts, the more common fossil stuff of teeth, bones, shells, scales, and so forth.

[Temujin]

I was gonna post this. Probably for the best though, last few science articles I posted were practically ignored.

Yeah, I saw this at work today. I tried to find some more detailed articles, but that seems to be the only one making the rounds around the web right now.

As for preservation of the fossils, I seem to recall something about how the geological processes going back further then the Cambrian probably destroyed a lot of the regions where that kind of fossilized life would have been preserved.

[Serafina]

Yes, widespread destruction of fossils seems more likely than simply bad preservation, simply because the timespan is so incredibly long. If the rare finds were only due to rare fossilization, it would have been an incredibly low rate - this way, it's appears to be somewhat less absurd.
Of course, that doesn't mean that these things left many fossils in the first place, but it just seems unlikely that a period of one and a half billion years leaves so little behind.

[Ilya Muromets]

Tectonic movements probably also contribute to it. I mean, a lot can happen in 2.1 billion years worth of plate shifting, and it's reasonable to conclude that even the best-preserved fossils might have been pulverized, melted, or buried too far for us to reach as the plates slid over, under, or against each other within that time period.

[Simon_Jester]

Is it possible that multicellular life evolved more than once? I mean, there's no evidence for it, but if multicelled organism emerged under unusual conditions two billion years ago, were wiped out because of some kind of chemical imbalance in their environment, then re-emerged in the late pre-Cambrian, that would tend to explain why we haven't found any in the period in between.

[Tasoth]

The independent evolution of multicellular life could happen multiple times, but it would be easier just to assume that these guys came first, thrived and then took a hit when conditions changed yet a portion of them survived. That surviving population could eventually recolonize where they used to be and then radiate into new forms as adaptation took place. And if the environment they were going back into was free of competitors they'd be able to expand into new niches as they evolved. So in a way, this could be seen as laying the ground work for the cambrian explosion. You have multicellular life that is coming back from the brink of extinction into a world with so many possibilities.

[Mayabird]

Is it possible that multicellular life evolved more than once? I mean, there's no evidence for it, but if multicelled organism emerged under unusual conditions two billion years ago, were wiped out because of some kind of chemical imbalance in their environment, then re-emerged in the late pre-Cambrian, that would tend to explain why we haven't found any in the period in between.

That was my first thought when I read it, actually. While yes, it would be very cool to know that multi-cellular life did evolve that early on, it's more exciting to me to think that if it did evolve twice, it might not be as hard to do as we had been fearing. If there is life out there in the big wide universe (and there had better be), it'd be more fun if it was more than just single cells in puddles. Although, just knowing that maybe increased free oxygen allows it to happen could work too.

And as people have said, this is all just speculation but speculation is fun.

[cosmicalstorm]

Is it possible that multicellular life evolved more than once? I mean, there's no evidence for it, but if multicelled organism emerged under unusual conditions two billion years ago, were wiped out because of some kind of chemical imbalance in their environment, then re-emerged in the late pre-Cambrian, that would tend to explain why we haven't found any in the period in between.

That was my first thought when I read it, actually. While yes, it would be very cool to know that multi-cellular life did evolve that early on, it's more exciting to me to think that if it did evolve twice, it might not be as hard to do as we had been fearing. If there is life out there in the big wide universe (and there had better be), it'd be more fun if it was more than just single cells in puddles. Although, just knowing that maybe increased free oxygen allows it to happen could work too.

And as people have said, this is all just speculation but speculation is fun.

There was a paper published last year which -- if I read it right -- basically stated that the emergence of complex organic molecules was the rule, and not the exception.
http://www.nature.com/nature/journal/v4 ... 08013.html

[Broomstick]

Is it possible that multicellular life evolved more than once? I mean, there's no evidence for it, but if multicelled organism emerged under unusual conditions two billion years ago, were wiped out because of some kind of chemical imbalance in their environment, then re-emerged in the late pre-Cambrian, that would tend to explain why we haven't found any in the period in between.

That was my first thought when I read it, actually. While yes, it would be very cool to know that multi-cellular life did evolve that early on, it's more exciting to me to think that if it did evolve twice, it might not be as hard to do as we had been fearing.

There is actually some (very) weak evidence that we are not the first group of multicelluar life on Earth. The previously mentioned Ediacara critters do not seem to have left any descendants (though this is hotly debated, apparently, among people who work with fossils of that era) and seem, from what little we know, to be very different than what are known to be our ancestors they might qualify as a separate rising of multicelluar life.

It is possible that fungi arose as multicelluars in a separate event from the lineage leading to plants and animals.

The Gabon group may be the ancestors of the Edicara, of every other multicelluar life form, or a separate "experiment" in multicelluar life that got knocked out by some extinction event.

And as people have said, this is all just speculation but speculation is fun.

Yes. Even more fun where there are some neat rocks to back some of it up.

[Mayabird]

Is it possible that multicellular life evolved more than once? I mean, there's no evidence for it, but if multicelled organism emerged under unusual conditions two billion years ago, were wiped out because of some kind of chemical imbalance in their environment, then re-emerged in the late pre-Cambrian, that would tend to explain why we haven't found any in the period in between.

That was my first thought when I read it, actually. While yes, it would be very cool to know that multi-cellular life did evolve that early on, it's more exciting to me to think that if it did evolve twice, it might not be as hard to do as we had been fearing. If there is life out there in the big wide universe (and there had better be), it'd be more fun if it was more than just single cells in puddles. Although, just knowing that maybe increased free oxygen allows it to happen could work too.

And as people have said, this is all just speculation but speculation is fun.

There was a paper published last year which -- if I read it right -- basically stated that the emergence of complex organic molecules was the rule, and not the exception.
http://www.nature.com/nature/journal/v4 ... 08013.html

Yeah, but molecules =/= multicellular life. I'm not talking about the emergence of life itself. I'm talking about the emergence of macro-scale life. As the article said, the previous oldest multi-cellular fossils were some embryo-looking things that were about 600 million years old. Life had been around on Earth for some three billion-ish years by then. If it really took about that long for cells to get over the hurdle of being single vs. clumping, how likely could it be that life elsewhere in the universe would never get over it?

It is possible that fungi arose as multicelluars in a separate event from the lineage leading to plants and animals.

The Gabon group may be the ancestors of the Edicara, of every other multicelluar life form, or a separate "experiment" in multicelluar life that got knocked out by some extinction event.

The Ediacara thingies though were recent enough that they could've had a common ancestor with the animal or whatever lines did survive. There was nothing to absolutely say that it wasn't just one event of cell sticking together relatively recently in geologic history. Heck, we still don't know if it was multiple events or if the complex big stuff was just lying low for a long time, but at least we know it didn't take three freaking billion years to happen once.

[Broomstick]

It is possible that fungi arose as multicelluars in a separate event from the lineage leading to plants and animals.

The Gabon group may be the ancestors of the Edicara, of every other multicelluar life form, or a separate "experiment" in multicelluar life that got knocked out by some extinction event.

The Ediacara thingies though were recent enough that they could've had a common ancestor with the animal or whatever lines did survive. There was nothing to absolutely say that it wasn't just one event of cell sticking together relatively recently in geologic history.

I don't pretend to understand all the evidence and science involved, but apparently there is a group of such scientist who, for the past 20-30 years (at least - that is how long I've been cognizant of the argument), have maintained that Ediacara is a separate case of multicelullarity from the current animal, plant, and fungal kingdoms. Just as there are those who say the fungi and the animals+plants represent separate instances of multicelluarity arising. My limited understanding is that this is based on body structures, but as I said, I don't completely understand the arguments. What it boils down to is that some maintain that the Ediacara, fungal, and animal/plant groups are all too structurally different to have a common multicelluar ancestor. Others say the Edicara are related to animal/plants, just a really, really early ancestor group. Presumably, regardless of who is right in that argument, they all have a common unicelluar ancestor if you go back far enough.

Although it is possible that life arose more than once on Earth - meaning it might be possible that some lineages are completely separate from the rest, though it seems very, very unlikely. Unless life can only result in an RNA/DNA based genetic code utilizing the same amino acids, in which every time it happens it comes out with the same genetic code... but until we find life elsewhere that we know is a separate occurrence of life it's hard to do more than speculate.

Heck, we still don't know if it was multiple events or if the complex big stuff was just lying low for a long time, but at least we know it didn't take three freaking billion years to happen once.

While this current find in Gabon is intriguing I think that there still needs to be some replicating of results by independent teams before we definitively say it's really that old a multicelluar life form. It seems likely to be confirmed, but for a find that extraordinary there needs to be extraordinary support.

[Johonebesus]

If there were single celled organisms that weren't part of our genetic and chemical lineage, how likely is it that they might go unnoticed? Wouldn't they fail to show up under normal chemical tests, and mightn't they be passed over as mundane bacteria under the microscope?

[Broomstick]

It all depends on their chemical composition. If they independently came up with RNA, DNA, and so forth then there might be no way to tell the difference. Otherwise... well, if they were VERY different we should have found them already, but even the most divergent life forms we've found on the planet so far still have a surprising amount of DNA in common with every other life form on the planet.

[Temujin]

I've heard some discussion that multiple forms of life arose on the early Earth, each with different DNA, and only our strain survived and flourished. There's also the possibility that a different strain exists as microbial life residing deep in the Earth. The sheer amount of life estimated to be down there now boggles the mind. I believe one estimate put it collectively weighing as much as all the life on the surface.

[Junghalli]

I heard about this on another forum. Very cool, and it really demonstrates just how big the gaps in our knowledge about past life are.

I remember reading from various sources that oxygen levels were lower during this period and increased prior to the Cambrian Explosion, that might be why it happened so late. Animals evolved, but they couldn't get very big without more abundant oxygen.

The sheer amount of life estimated to be down there now boggles the mind. I believe one estimate put it collectively weighing as much as all the life on the surface.

That would be something if true, do you remember the source of that estimate?

[Temujin]

I want to say it was originally on TV, either Discovery Science or NatGeo as along with BBC that's about all I'm watching anymore.

A quick Google turned up this link though. It's only an Abstract, but...

Exploration of deep intraterrestrial microbial life: current perspectives

ABSTRACT

Intraterrestrial life has been found at depths of several thousand metres in deep sub-sea floor sediments and in the basement crust beneath the sediments. It has also been found at up to 2800-m depth in continental sedimentary rocks, 5300-m depth in igneous rock aquifers and in fluid inclusions in ancient salt deposits from salt mines. The biomass of these intraterrestrial organisms may be equal to the total weight of all marine and terrestrial plants. The intraterrestrial microbes generally seem to be active at very low but significant rates and several investigations indicate chemolithoautotrophs to form a chemosynthetic base. Hydrogen, methane and carbon dioxide gases are continuously generated in the interior of our planet and probably constitute sustainable sources of carbon and energy for deep intraterrestrial biosphere ecosystems. Several prospective research areas are foreseen to focus on the importance of microbial communities for metabolic processes such as anaerobic utilisation of hydrocarbons and anaerobic methane oxidation.

[cosmicalstorm]

I'd also be interested in learning more about the total amount of life existing underground.

[Commander Xillian]

This is really cool, thanks for the info OP. I now need to toss this at my local creationist whackjob...

[SCRawl]

This is really cool, thanks for the info OP. I now need to toss this at my local creationist whackjob...

Pfft. You're all just part of the Evolutionist Conspiracy, and nothing will convince a True Believer otherwise.

(Seriously, don't waste your time throwing good arguments at a creationist whackjob -- use that time better, by, say, digging a hole and filling it in again repeatedly.)

[Akhlut]

It all depends on their chemical composition. If they independently came up with RNA, DNA, and so forth then there might be no way to tell the difference.

Actually, we probably could. There's no reason for our codons to code for the amino acids that they do. It is entirely plausible you'd see codons doing different things and arranged in different ways (the first position being the wobble position, for instance).

Otherwise... well, if they were VERY different we should have found them already, but even the most divergent life forms we've found on the planet so far still have a surprising amount of DNA in common with every other life form on the planet.

The conservation of codons helps prove that relationship, BTW.